In the remote sensing/aerial imaging industry, imagery is used to capture views of a geographic area and to be able to measure objects and structures within the images as well as to be able to determine geographic locations of points within the image. These are generally referred to as “geo-referenced images” and come in two basic categories:
Vertical Imagery—these images are captured with the camera pointed vertically downward and thus generally only capture the tops of structures.
Oblique Imagery—these images are captured with the camera aimed at an angle so as to capture the sides of structures as well as the tops.
Most vertical imagery is processed in order to fit a mathematically rectangular projection or map. This process is known as ortho-rectification and attempts to create an appearance as if the sensor were directly above each pixel in the image. The resulting image is known as an ortho-photo. Since the images are mathematically projected, they can be combined into a seamless mosaic. The resulting composite image is called an ortho-mosaic. The term “ortho image” is used to denote an image that is either an ortho-photo image or an ortho-mosaic image.
Because they are captured looking straight down, an ortho-photo or ortho-mosaic contains a view of the world to which we are not accustomed. As a result, many people have difficulty determining what it is they are looking at in the image. For instance, they might have difficulty distinguishing between two commercial properties since the only thing they can see of the properties in the ortho-mosaic is their roof tops, where as most of the distinguishing properties are on the sides of the buildings. An entire profession, the photo interpreter, has arisen to address these difficulties as these individuals have years of training and experience specifically in interpreting what they are seeing in ortho imagery.
Since an oblique image, by definition, is captured at an angle, it presents a more natural appearance because it shows the sides of objects and structures—what we are most accustomed to seeing. In addition, because oblique images are not generally ortho-rectified, they are still in the natural appearance that the camera captures as opposed to the mathematical construction of the ortho image. This combination makes it very easy for people to look at something in an oblique image and realize what that object is. Photo interpretation skills are not required when working with oblique images.
In the past, people have used geo-referenced oblique images to measure objects and structures within the images as well as to be able to determine geographic locations of points within the image when preparing estimates for a variety of construction projects, such as roadwork, concrete work, and roofing. Estimating construction projects using software is desirable in that it increases the speed at which an estimate can be prepared, and reduces labor and fuel costs associated with on-site visits. For roofing, this is even more important since measuring an actual roof can be a costly and potentially hazardous job—especially with steeply pitched roofs.
With respect to estimating roofing projects, software for measuring the pitch of a roof of a building using a geo-referenced oblique image has been developed. This software causes a computer system to display an oblique image, and provides a “pitch tool” to measure the area and pitch of a roof in an oblique image. To measure pitch, the software permits the user to (1) click a pitch tool, (2) measure a height from the ground to the roofs eave by clicking at the ground, dragging to the eave, and then releasing the mouse button, (3) measure the height from the ground to the roof's peak, by clicking at the ground, dragging to the peak, and then releasing the mouse button, and (4) measure a distance of a ridge-line by clicking where the user last released the mouse, dragging along the ridge-line to the opposite end of the roof, and then releasing the mouse button.
The prior software displayed an area outline and a measurement on the image, and the following measurements appeared on a status bar: area, eave height, peak height, roof angle, roof, and roof pitch (rise over run).
Software for measuring the slope of a roof without using elevation data has also been developed. The software allows a user to measure slope (change in elevation between two points) without using elevation data by clicking a point in a first image at which to start the slope measurement. A small red crosshair marked the starting point. A corresponding point was clicked in a second image, and then a point in the first image at which to end the slope measurement was clicked. A line connected the starting and ending points and a dialog box showed a slope, a distance, a height difference and a pitch.
However, the prior software did not include any manner of automatically classifying roof elements, such as ridge lines, drip edges or eaves and the like so that reports including cumulative lengths of such roof elements could be automatically or semi-automatically prepared. It is to such an improvement that the present disclosure is directed.